Previously disclosed is a magnetic head device that has a slider that faces a magnetic recording medium and a magnetic function unit provided in an end portion of a ring side of a tray of the slider. The magnetic head device records a magnetic signal in the magnetic recording medium such as a hard disk and reads out the magnetic signal recorded in the magnetic recording medium. The magnetic function unit has a reproducing function unit where an MR effect or a GMR effect is used and a recording function unit where magnetic materials such as a york, a coil and the like are thin-filmed.
The slider of the magnetic head device is suppressed on the surface of the magnetic recording medium by an elastic member such as a load beam, but when the magnetic recording medium rotates, the slider levitated from the magnetic recording medium by an air stream (air pairing) flowing between the surface thereof and the slider, thus predetermined levitation height is set between the magnetic function unit and the magnetic recording medium.
In this type of magnetic head device, a positive pressure surface that generates a levitation pressure by the air stream and a negative pressure generating surface retreats farther than the positive pressure surface are formed on sides of the magnetic recording medium in the slider that faces each other. The slider has an adequate levitation attitude on the surface of the magnetic recording medium by a balance between the levitation pressure exerted on the positive pressure surface and an absorption force to the magnetic recording medium generated on the negative pressure generating surface to stabilize the levitation height.
In order to enhance a magnetic recording density to the magnetic recording medium, and speed-up the recording speed and the reproducing speed, the levitation height from the magnetic function unit is generally set to be lowered as much as possible.
In the magnetic head device according to JP-A-10-283622 (U.S. Pat. No. 6,021,020) described below, in a facing side that faces the magnetic recording medium of the slider, a comparatively deep cratering is formed in an intermediate part of an anterior-posterior direction. The positive pressure surface has a comparatively wide area that is formed at a front part, which is farther than the cratering. The positive pressure surface has a comparatively small area that is formed at a rear part farther than the cratering. This magnetic head device decreases the levitation height by generating the levitation pressure only in a front part and a rear part of the slider without substantially generating the levitation pressure in the middle cratering part.
In the known magnetic head device, the variation of the levitation height that is changed by the air density has a low levitation of the slider. When a levitation distance of the slider is shortened with respect to the magnetic recording medium, the levitation height can be lowered by fluctuating in correspondence with the lowering of the air density based on the altitude difference. When the known magnetic head device is used at high altitudes, such as in an aircraft, the slider can potentially contact the surface of the magnetic recording medium. This increases the possibility that the magnetic recording medium or the magnetic head device rises will be damaged.
In the magnetic head device according to Patent Document 1 described above, the low levitation height is realized by generating the levitation pressure only in the front part and the rear part of the slider. However, in this configuration, when the air density of the operating environment is lowered, the levitation height of the slider is also lowered, thus damage may occur.